Our American Cousin is a play in three acts by Tom Taylor. The play is a farcical comedy whose plot is based on the introduction of an awkward, boorish American to his aristocratic English relatives. It premiered at Laura Keene’s Theatre in New York City on October 15, 1858.

The play’s most famous performance came seven years later, however, at Ford’s Theatre in Washington, D.C. on April 14, 1865. Halfway through Act III, Scene 2, the character Asa Trenchard (the titular cousin), played that night by Harry Hawk, utters one of the play’s funniest lines — however little sense it makes out of context:“Don’t know the manners of good society, eh? Well, I guess I know enough to turn you inside out, old gal—you sockdologizing old man-trap.”

During the raucous laughter that followed this line, John Wilkes Booth, an actor who received his mail at Ford’s Theater but who was not in the cast of Our American Cousin, assassinated Abraham Lincoln. He chose the timing in hopes that the sound of the laughter would mask the sound of his gunshot. He then leaped from Lincoln’s box to the stage, breaking his leg, and dragged himself out. As he leapt, Booth shouted “Sic semper tyrannis!” Others in the audience heard it as: “The South is avenged!”Before its history was changed by Lincoln’s assassination, the play had already made a cultural impact.

The character Lord Dundreary became popular for the absurd riddles he propounded. “Dundrearyisms,” twisted aphorisms in the style of Lord Dundreary (e.g. “birds of a feather gather no moss”), also enjoyed a brief vogue. The same character’s style of beard – long, bushy sideburns – gave the English language the word “dundrearies.”For the entire text: Gutenberg.org